title: LRRK2 and parkin immunoreactivity in multiple system atrophy inclusions.
abstract: Certain genetic defects in LRRK2 and parkin are pathogenic for Parkinson's disease (PD) and both proteins deposit in the characteristic Lewy bodies. LRRK2 is thought to be involved in the early initiation of Lewy bodies. The involvement of LRRK2 and parkin in the similar cellular deposition of fibrillar alpha-synuclein in glial cytoplasmic inclusions (GCI) in multiple system atrophy (MSA) has not yet been assessed. To determine whether LRRK2 and parkin may be similarly associated with the abnormal deposition of alpha-synuclein in MSA GCI, paraffin-embedded sections from the basal ganglia of 12 patients with MSA, 4 with PD and 4 controls were immunostained for LRRK2, parkin, alpha-synuclein and oligodendroglial proteins using triple labelling procedures. The severity of neuronal loss was graded and the proportion of abnormally enlarged oligodendroglia containing different combinations of proteins assessed in 80-100 cells per case. Parkin immunoreactivity was observed in only a small proportion of GCI. In contrast, LRRK2 was found in most of the enlarged oligodendroglia in MSA and colocalised with the majority of alpha-synuclein-immunopositive GCI. Degrading myelin sheaths containing LRRK2-immunoreactivity were also observed, showing an association with one of the earliest oligodendroglial abnormalities observed in MSA. The proportion of LRRK2-immunopositive GCI was negatively associated with an increase in neuronal loss and alpha-synuclein-immunopositive dystrophic axons. Our results indicate that an increase in LRRK2 expression occurs early in association with myelin degradation and GCI formation, and that a reduction in LRRK2 expression in oligodendroglia is associated with increased neuronal loss in MSA.
authors.affiliation: Prince of Wales Medical Research Institute, Barker Street, Randwick, NSW, 2031, Australia.
authors.forename: Yue
authors.initials: Y
authors.lastname: Huang
authors.forename: Yun Ju Christine
authors.initials: YJ
authors.lastname: Song
authors.forename: Karen
authors.initials: K
authors.lastname: Murphy
authors.forename: Janice L
authors.initials: JL
authors.lastname: Holton
authors.forename: Tammaryn
authors.initials: T
authors.lastname: Lashley
authors.forename: Tamas
authors.initials: T
authors.lastname: Revesz
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Gai
authors.forename: Glenda Margaret
authors.initials: GM
authors.lastname: Halliday
mesh_terms: D000368:Aged; D001369:Axons / Q000378:metabolism / Q000473:pathology; D001479:Basal Ganglia / Q000378:metabolism / Q000473:pathology; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007150:Immunohistochemistry; D002479:Inclusion Bodies / Q000378:metabolism* / Q000473:pathology; D020772:Internal Capsule / Q000378:metabolism / Q000473:pathology; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000378:metabolism* / Q000473:pathology; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology; D009410:Nerve Degeneration / Q000378:metabolism / Q000473:pathology; D010300:Parkinson Disease / Q000378:metabolism* / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011699:Putamen / Q000378:metabolism / Q000473:pathology; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D051844:alpha-Synuclein / Q000378:metabolism
chemical_list: D025801:Ubiquitin; D051844:alpha-Synuclein; D044767:Ubiquitin-Protein Ligases; C111567:parkin protein; C495280:LRRK2 protein, human; D000071158:Leucine-Rich Repeat Serine-Threonine Protein Kinase-2; D017346:Protein Serine-Threonine Kinases